Amyloid precursor protein (APP) is a type I transmembrane glycoprotein that is overexpressed in various cancer types and has been reported to play key roles in promoting tumor progression. In this study, we investigated the subcellular expression, biological function, and potential therapeutic strategies targeting the ADAM10-APP axis in colorectal cancer (CRC). Single-cell RNA sequencing and spatial transcriptomic analysis were performed to elucidate the enrichment of APP expression in CRC. Liquid chromatography-mass spectrometry (LC-MS) surfaceome analysis was conducted on 14 CRC cell lines to validate APP expression on the cell surface. A tissue microarray (TMA) was used to validate the surface expression of APP. Western blotting, 3D culture, invasion and migration assays, as well as a nude mouse model, were utilized to investigate the biological function of APP. Additionally, an antibody-drug conjugate (ADC) assay targeting APP was utilized to explore its therapeutic potential in CRC. Multi-omics data revealed that APP is highly expressed in CRC and is specifically enriched in epithelial cells. Through proteomic profiling of human CRC cell lines and validation in a tissue microarray consisting of 140 CRC tumors, we identified APP as significantly enriched on the cell surface. Functional studies showed that knockdown or knockout (KO) of APP in CRC cells led to marked reductions in cell proliferation, colony formation, and invasiveness, effects that were in part reversible upon the addition of soluble APP (sAPP). In xenograft models of colorectal cancer (CRC), APP-KO HCT116 tumor-bearing mice exhibited significantly reduced tumor growth and tumor initiation frequency compared to control HCT116 tumor-bearing mice. We further demonstrated that treatment of CRC cells with GI254023X, a selective ADAM10 inhibitor, increased cancer cell surface APP expression. A combination therapy of GI254023X with an APP antibody conjugated to monomethyl auristatin F (APP-ADC-MMAF) resulted in superior anti-cancer efficacy compared to either treatment alone. APP is highly expressed on the surface of CRC cells and promotes tumor progression, making it a potential target for ADC therapies. Inhibition of ADAM10 reduces APP cleavage and further enhances its surface expression, highlighting a promising treatment strategy for CRC. Rongzhang Dou, Hanwen Xu, Ricardo A. León-Letelier, Ali H. Abdel Sater, Yihui Chen, Jody Vykoukal, Makoto Kobayashi, Clemente Aguilar-Bonavides, Johannes F. Fahrmann, Hiroyuki Katayama, Samir M. Hanash. Dual targeting of amyloid precursor protein with α-secretase inhibitor and antibody-drug conjugate synergistically reduces tumor progression in colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 6740.
